A Semi‐Analytic‐FEM Hybrid Model for Simulating UT Configurations Involving Complicated Interactions of Waves with Defects

A hybrid model is developed combining advantages of both semi‐analytical and numerical methods. Most of the propagation is computed semi‐analytically (pencil method, code Civa), while wave — defect interaction is computed numerically (FEM, code Athena) in a small region surrounding the defect. Both codes exchange results required to predict responses from defects through an integral formula extending Auld’s principle to the transient case. The theory and its implementation are discussed. Examples illustrate its interest in UT simulations involving complicated interactions.